1. Field of the Invention
The present invention relates to an image pickup apparatus capable of detecting a moving object.
2. Description of Related Art
A wide variety of image pickup apparatuses have been proposed.
The proposed image pickup apparatuses having a wide dynamic range include those having pixels for pickup operation, each pixel including a photoelectric conversion element and a logarithmic converter which gives an output by natural-logarithmical photoelectric conversion of an amount of light incident on the photoelectric conversion element.
U.S. Pat. No. 5,241,575 discloses such image pickup apparatus. The disclosed image pickup apparatus is provided with, for example, photodiodes as the photoelectric conversion elements and MOS transistors for logarithmic conversion as the logarithmic converters. The U.S. Pat. No. 5,241,575 also discloses pixels incorporating an integration circuit for accumulating the output of the logarithmic converter.
Proposed logarithmic conversion-type image pickup apparatuses include those capable of cancelling irregularities of sensitivity among pixels. This type of image pickup apparatus is disclosed in Japanese unexamined laid-open patent publication No.2001-94878. The disclosed apparatus is capable of cancelling irregularities of sensitivity among pixels without employing a technique of detecting the irregularities of sensitivity among pixels by irradiating the pixels with uniform light.
In the image pickup technology field, research has been conducted on the detection of a moving object in order to monitor, for example, intruders and the like. A background finite difference method (method of detecting a moving object by use of difference between a background image and an inputted image) was proposed for this purpose. Japanese unexamined laid-open patent publication No.7-336694(336694/1995) discloses a method of detecting a moving object according to such background finite difference method.
However, for detection of a moving object, conventional image pickup apparatuses involve a complicated processing of signals from an image pickup sensor. Now it is desired to develop an image pickup apparatus capable of easily detecting a moving object without executing such complicated processing of signals. Such image pickup apparatus is easily applicable for technologies in the monitoring field.